In this application, the long-term goal is the development of an effective tumor-targeting lipoplex for systemic treatment of pancreatic cancer (PanCa), which has one of the worst prognosis of all human malignancies. Our previous studies indicate that cancer cells can be sensitized to radiation/chemotherapy via p53 restoration ,using a tumor-targeting liposomal gene delivery system. For the delivery of the wtp53 gene, as well as other genes, we have developed a ligand, tumor-targeting liposome complex, a nanoparticle delivery system (NDS). This resulted not only in tumor growth inhibition and/or increased survival, but also, in complete, long-term elimination of some tumors in mouse models of cancer when combined with either radiation or chemotherapy. To further achieve improvement in transfection efficiency of our NDS, recently we have designed the inclusion of a pH sensitive cationic HK peptide (histidylated oligolysine) in the complex to enhance DNA release from the endosome. One of the advantages of our NDS is that it can be broadly employed for numerous tumor types. Thus, in this application we will focus on PanCa. The major aims of this STTR I proposal are to optimize this modified complex and evaluate its transfection efficiency in vitro and its in vivo targeting ability for PanCa tumors. The assessment of this novel NDS with respect to its potential for efficient tumor-targeting delivery and antitumor efficacy can be cumbersome when based solely on biological assays, particularly in regards to product release criteria for production of therapeutic agents. Consequently, the development of methods for characterizing NDS using physical parameters would be essential. Joining forces with Dr. John Dagata at NIST, we propose to use advanced imaging analysis including atomic force microscopy, electric force microscopy, and phase imaging to characterize the NDS and correlate the results of these physical analyses with the observed biological effects of the complex. This will allow us to leverage our efforts in a pioneering attempt to bridge the gap between two distinct technologies, thus developing new engineering methodologies to characterize, design and improve therapeutic delivery systems. In addition, establishing new technologies to assess the physical characteristics of NDS will also aid in developing more precise product release criteria for these biological therapeutics.